Also known as:superseding intervening factors · superseding cause · intervening cause
Written by attorneys · grounded in primary & secondary sources — see below
An intervening force or act of a third person that by its operation prevents antecedent negligence from remaining a legal cause of harm. The force must actively operate after the negligent conduct and render the harm too remote or different in kind from the risk originally created. Liability is cut off only when the intervention meets the criteria that render it superseding under the governing tests.
Sources & Authorities
How it applies
Common Examples
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Misrouted Emergency Call
Alpha Communications negligently routed all 911 calls from County A to an unfamiliar County B dispatcher. When a neighbor reported a fire at Rebecca's home, the dispatcher misidentified the address and issued contradictory directions that delayed firefighters by more than twenty minutes. The fire spread further and caused additional damage. The dispatcher's cascading errors constituted a superseding intervening factor that relieved Alpha of liability for the expanded harm.
Unsecured Sculpture Photograph
Plains Craft left a large freestanding sculpture unsecured at a crowded reception despite prior toppling incidents at other museums. Wesley organized the event without barriers or monitoring. Odell independently directed guests including Walker to lean against the base for a posed photograph, causing the sculpture to topple and injure Walker. Odell's deliberate direction was a normal consequence of the unsecured display and did not operate as a superseding intervening factor.
Select any source to read its text and confirm it supports the definition.
Restatements
Course Outlines
Herbicide Drift From Overapplication
Lake Growers supplied Harrison with herbicide in containers whose labels omitted the required dilution ratio. Harrison directed Vera to spray before rain arrived. Vera doubled the dosage without reading the full label and applied the mixture in moderate wind, causing vapor drift that destroyed Justin's adjacent organic crops. Vera's hurried overapplication was a normal response to the incomplete label and did not qualify as a superseding intervening factor.
Upside-Down Maintenance Panel
Union Jet designed an aircraft maintenance panel without physical keying despite engineers warning that rushed mechanics often skipped manuals. Coastal Space assigned Zane to install the panel during a compressed window. Zane installed it upside-down without consulting the manual, causing an in-flight systems failure that injured passenger Erin. Zane's installation error was a foreseeable risk created by the design and did not constitute a superseding intervening factor.
Wrong Medication From Similar Packaging
Imperial Pharmaceuticals shipped trial medication to Fair Drug in packaging nearly identical to a stocked sedative despite internal memos flagging staff confusion risks. During a short-staffed rush, nurse Isaiah selected and administered the wrong drug to Patrick. Patrick lost consciousness while driving home and suffered crash injuries. Isaiah's selection error was a normal consequence of the similar packaging and did not operate as a superseding intervening factor.
Effort To Avert Sculpture Collapse
Plains Craft displayed an unsecured sculpture at a crowded event. When guests began leaning on the base, a third person attempted to steady the sculpture to prevent it from toppling onto nearby visitors. The effort caused the sculpture to fall in a different direction and injure Walker. The third person's normal effort to avert the threatened harm was not a superseding intervening factor.
Common questions
Frequently Asked
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When does negligent conduct by a third person fail to break the chain of causation?+
Negligent conduct by a third person fails to break the chain when the original actor should have realized that a third person might act in that manner, when a reasonable person would not regard the act as highly extraordinary, or when the act is a normal consequence of the situation created by the original negligence and is not extraordinarily negligent.
Supporting sources
Does an intervening act that produces harm different in kind automatically qualify as superseding?+
No. The difference in kind of harm is only one consideration among several. Courts also examine whether the intervention appears extraordinary after the fact, whether it results from a third person's wrongful act, and the degree of the third person's culpability.
Supporting sources
How does foreseeability affect whether an intervening force is superseding?+
When the original negligent conduct creates or increases a foreseeable risk of harm through the intervention of another force and remains a substantial factor in causing the harm, the intervention does not qualify as superseding.
Supporting sources
Is a victim's or third person's normal effort to avoid threatened harm superseding?+
No. Normal efforts by the victim or a third person to avert harm threatened by the actor's negligence are not superseding even when those efforts themselves produce additional harm.
Supporting sources
2 Cal. App. 3d 203, 82 Cal. Rptr. 598 (1969)Criminal Law
…that death. “The proximate cause of death is that cause which, in natural and continuous sequence, unbroken by any efficient intervening cause, produces the death, and without which the result would not have occurred. It is the efficient cause—the one that necessarily sets in operation the factors that accomplish the death.”…